Methods and apparatus for X-ray therapy



Aug. 26, 1958 J. w. CLARK METHODS AND APPARATUS FOR X-RAY THERAPY FiledMarch 25, 1955 2 Sheets-Sheet 1 mi mm .mw

INVENTOR. file N W Came/c Aug. 26, 1958 J. W/CLARK METHODS AND APPARATUSFOR X-RAY THERAPY 2 Sheets-Sheet 2 INVENTOR. fa/m W C2 48% BY %mu-A)flrrae/vzz Filed March 25, 1955 METHODS AND APPARATUS FOR X-RAY THERAPYJohn W. Clark, Santa Monica, Calif., assignor to Litton industries ofCalifornia, Beverly Hills, Calif.

Application March 25, 1955, Serial No. 496,732

14 Claims. (Cl. 250-64) This invention relates to methods and apparatusfor X-ray therapy and more particularly to therapeutic X-ray apparatuswherein a radioactive source of relatively soft or low voltage X-rays isutilized to provide a boresight for aligning a source of relatively hardor high voltage X-rays or gamma rays with an object to be irradiated.For purposes of simplicity, the term X-rays will be utilized hereinafteras generic to both X-rays and gamma rays, since gamma rays are inreality only exceptionally hard X-rays.

The therapeutic value of X-rays in the treatment of tumors and otherphysical disorders has longbeen recognized by the medical profession. Ingeneral, X-ray therapy, as contrasted with the diagnostic application ofX-rays, requires extremely intense irradiation of a relatively smallarea which defines the region to be treated.

ing extremely hard X-rays or gamma rays, these X-ray sources includingboth exceptionally high voltage electronic X-ray apparatus and nucleonicX-ray apparatus employing materials such as radioactive cobalt, forexample.

Although each of the above forms of apparatus has successfully provenits therapeutic value, there is at least one serious disadvantageattendant their use, namely, the fact that it is difficult to align theX-ray source with the particular area to be irradiated. Morespecifically, in setting up the apparatus for a treatment it is usuallynecessary to align the X-ray source with a relatively small area withinthe patients body; however, owing to the fact that the relative positionof organs or tissue within the body tends to change as the body assumesvarious positions, it is extremely diflicult to foretell from anexternal examination the precise location of the tissue to be treated.

in the past it has been proposed that the high voltage X-ray source beutilized first in combination with a fluoroscope or X-ray plate fordetermining the position of the tissue to be treated, and thereafter asa therapeuticinstrument. As a rule, however, this proposal is rejectedfor several reasons. Firstly, the maximum amount of radiation to whichthe body may be subjected is relatively limitedglaccordingly, theutilization of the therapy apparatus for positioning the patientappreciably decreases the amount of exposure time available for therapy.Secondly, irradiation of healthy tissue may also produce harmfulafterefiects. Thirdly, therapeutic X-ray apparatus is not in generalamenable to use with fluoroscopic apparatus or X-ray plates owing to thefact that the-high voltage rays used for therapy do not give sufiicientcontrast to enable the radiologist to locate the site of irradiationfiuoroscopically. in other words, the various portions of the body aresubstantially equally transparent to X-rays or gamma rays of relativelyshort Wavelength.

Owing to the foregoing limitations on the use of therated States PatentF 2,849,621 Patented Aug. 26, 1958 ice peutic X-ray apparatus forproperly positioning the patient, it has become common practice toemploy anatomical surveying and its concommitant precise measurements todetermine the location of the tissue to be treated. However, thistechnique is relatively expensive and time consuming, and requires askilled anatomist to determine the area to be irradiated. Of even moreimportance is the fact that in any individual case, the area selectedfor irradiation may be incorrect owing to the fact that the basicmeasurements utilized in anatomical surveys are based to some extent onstatistics.

The present invention, on the other hand, obviates the above and otherdisadvantages of the prior art therapeutic X-ray apparatus by providingmethods and apparatus which are utilizable in conjunction with a sourceof high energy X-rays for initially determining the location of tissueto be subsequently treated by high energy radiation. According to thebasic concept of the invent-ion there is provided a therapeutic X-rayapparatus wherein a radioactive source of relatively low voltage X-raysis utilized as a boresight for aligning a source of relatively highvoltage X-rays with an object to be irradiated. More specifically, thereis provided a high voltage therapeutic X-ray apparatus which includes asone of its elements a radioactive source of low voltage X-rays, thislatter source being movable to a point coincident with the center lineof the high voltage X-ray beam.

In operation, according to the methods of the invention, the radioactivesource is first utilized in cooperation with a fiuoroscope, for example,to align the center line of the high voltage X-ray beam with the centerof the region to be irradiated, after which the associated masks andcones of the high voltage X-ray source are adjusted so that only thedesired predetermined area will be visible to the high voltage X-raybeam. The low voltage radioactive source is then withdrawn from theradiation cone of the high voltage source after which the high energysource is actuated to irradiate the area to be treated.

According to the invention the methods and apparatus herein disclosedare equally applicable to both electronic therapeutic X-ray apparatusand nucleonic or radioactive therapeutic X-ray apparatus. It will alsobe recognized; of course, that the low voltage radioactive sourceemployed as the boresightlfor the therapeutic machine may be housedwithin the therapeutic apparatus itself or may be housed, in anassociatedequiprnent adapted to cooperate With existing therapeuticX-ray apparatus.

It is therefore an object of the invention to provide.

Another object of the invention is to provide a high voltage therapeuticX-ray apparatus which employs a radioactive source of relatively lowvoltage X-rays as a boresight for aligning the therapeutic apparatuswith an object to be irradiated.

It is also an object of the invention to provide a therapeutic X-rayapparatus which utilizes a relatively low voltage radioactive source,movable into a position coincident with the center line of thetherapeutic X-ray beam, for orienting the therapeutic X-ray beam withrespect to a predetermined area to be irradiated.

A further object of the invention is to provide a therapeutic X-rayapparatus which includes as one of its elements a radioactive auxiliarysource of low voltage X-rays, the auxiliary source being adapted toproject a beam of relatively soft X-rays along the axis of thetherapeutic X-ray beam which is produced when the therapeutic X-raysource is actuated.

Still another object of the invention is to provide methods for aligninga therapeutic X-ray apparatus with 3 an object to be irradiated withhigh voltage X-rays by first radiographically aligning the object with alow voltage X-ray beam emitted from a radioactive source positionedalong the center line of the high voltage X-ray beam.

A still further object of the invention is to provide methods foraligning a therapeutic X-ray apparatus with an object to be irradiatedby first irradiating the object with low voltage X-rays from anauxiliary radioactive source, radiographically observing the position ofthe object to be irradiated with respect to the position of thetherapeutic X-ray source, and moving the object relative to thetherapeutic source until the object lies within the cone which definesthe therapeutic X-ray beam.

The novel features which are believed to be characteristic of theinvention, both as to its organization and method of operation, togetherwith further objects and advantages thereof, will be better understoodfrom the following description considered in connection with theaccompanying drawings in which several embodiments of the invention areillustrated by way of example. It is to be expressly understood,however, that the drawings are for the purpose of illustration anddescription only, and are not intended as a definition of the limits ofthe invention.

Fig. 1 is a schematic view, partly in section, of a therapeutic X-rayapparatus, which includes a nucleonic high voltage therapeutic X-raysource and one embodiment of the novel alignment device of theinvention;

Figs. 2 and 3 are isometric views of alignment sights which may beemployed with the therapeutic X-ray apparatus of the invention;

Fig. 4 is a sectional view of a modified form of nucleonic therapeuticX-ray apparatus, according to the invention; and

Figs. 5 and 6 are schematic views, partly in section, of a therapeuticX-ray apparatus according to the invention which utilizes an electronicX-ray source to provide the therapeutic X-ray beam.

With reference now to the drawings, wherein like or corresponding partsare designated by the same reference characters throughout the severalviews, there is shown in Fig. 1 a therapeutic X-ray apparatus whichutilizes the novel X-ray boresight of the invention for aligning aparticular area within a patient 10 with the axis of the therapeuticX-ray beam. Basically, the therapeutic X-ray apparatus includes fourprincipal components, namely; a radioactive source 14, which may beradioactive cobalt, for example, for generating a therapeutic X-raybeam, a housing assembly, generally designated 16, for encapsulating andshielding source 14, a radioactive source 18 of relatively soft or lowvoltage X-rays which is utilized for aligning the therapeutic beam withan object to be irradiated, and an actuating mechanism, generallydesignated 20, for moving source 18 to a position coincident with theaxis of the therapeutic X-ray beam.

As shown in Fig. 1, housing assembly 16 includes a massive shieldingmember 22 for containing therapeutic X-ray source 14, shielding member22 preferably being constructed of a relatively heavy material such aslead and having a conically shaped aperture 23 communicating betweensource 14 and the exterior of member 22. In operation, as will be moreevident from the description set forth hereinbelow, passage 23 isoperative as a beam forming channel so that the therapeutic X-ray beamis projected concentric with the axis 24 of passage 23. In addition,housing assembly 16 also includes a shutter mechanism, generallydesignated 26, for selectively withdrawing a lead shutter 28, whichnormally blocks passage 23, into an adjacent cavity 30 in member 22. Inthe particular embodiment shown in Fig. I shutter 28 is actuated througha rack and pinion mechanism 32 affixed to the outer periphery of member22. It is clear, of course, that the pinion may be rotated either 4manually or through an associated motor driven mechanism, not shown.

According to the invention, low voltage radioactive source 18 ispreferably composed of thulium or a similar radioactive isotope suitablefor low energy radiography, and is normally postioned within a shieldingcavity 34 in member 22, substantially as shown, so that radiation fromthe low energy source is normally precluded from radiating into thesurrounding area. In the embodiment of the invention shown in Fig. 1,source 18 is connected to actuator mechanism 20 through a push rod 36which is axially movable in a bearing 38, push rod 36 constituting theplunger of a solenoid 40 which is energizable upon closure of a switch42 to project source 18 to a position coincident with axis 24 of thetherapeutic X-ray beam. In order to insure that source 18 is properlypositioned relative to axis 24, push rod 36 includes a relatively thicklower region, as viewed in the drawings, which bottoms againstthe lowerend of bearing 38 when solenoid 40 is actuated. It will be recognized bythose skilled in the art, of course, that the actuator mechanism mayinclude other mechanical devices, such as a return spring for example,to make the actuator mechanism completely fail safe.

Consider now the operation of the therapeutic X-ray apparatus of theinvention in locating and treating a particular region within a patient.The entire therapeutic X-ray apparatus and the patient are firstpositioned relative to each other so that axis 24 is directed toward thegeneral location of the tissue or organ to be treated. An X-ray filmcassette or fluoroscope 44 is then positioned on the side of the patientopposite the therapeutic X-ray apparatus after which switch 42 isclosed, thereby projecting low voltage X-ray source 18 into its positioncoincident with axis 24. As a consequence thereof the pertinent regionof the patients body is illuminated with relatively soft X-rays or gammarays which are of sutficiently low energy to produce a good X-raypicture of the area illuminated.

If it is assumed that a fluoroscope is employed in conjunction with thetherapeutic X-ray boresight of the invention, source 18 provides afluoroscopic image having good contrast, or in other words, an image inwhich the various elements of the body are readily discernible.Accordingly, the operator may readily determine the internal location ofthe tissue to be treated and move the patient and therapeutic apparatusrelative to each other until axis 24 is aligned with this tissue.Thereafter, associated masks and cones, not shown in Fig. 1 for purposesof simplicity, are adjusted so that only the desired area is irradiated.

When the foregoing steps have been carried out switch 42 is againreturned to its normal or open position, thereby returning low voltagesource 18 to its shielded position within cavity 34. Shutter mechanism26 is then actuated to withdraw shutter 28 into cavity 30, whereby thedesired region within the patient is exposed to the high energytherapeutic X-ray beam from source 14. At the conclusion of thetreatment shutter mechanism 26 is again actuated to return shutter 28 toits normal position within aperture 23, thereby shielding the patientfrom further irradiation.

It will be recognized from the foregoing description that radioactivesource 18 is employed as a boresight for aligning the therapeutic X-raybeam with a particular region to be irradiated. It will also berecognized, however, that source 18 produces a relatively wide beamwhich is delimited only by its position with respect to the right handend of passage 23, as viewed in Fig. 1, or if associated masks or conesare utilized, by its position with respect to the openings in theseelements. It is clear, therefore, that to utilize source 18 for aligningaxis 24 with the object to be irradiated some mechanism should beprovided to indicate the point on fluoroscope 44 intercepted by axis 24.In other words, even though the particular tissue to be treated is madevisible on the fluoroscope by virtue of the low energy radiation fromsource 18, a sight should be provided to indicate the positional errorbetween the tissue to be treated and axis 24.

With reference now to Figs. 2 and 3, these are shown two forms of sightswhich may be removably mounted at the end of aperture 23 in thetherapeutic apparatus of Fig. l, or in one of the associated cones, forindicating to the operator the location of the axis of the therapeuticX-ray beam. Referring now with particularity to Fig. 2 there isillustrated a cross hair sight which includes a mounting ring 50 whichis adapted to be mounted concentrically with one of the cones utilizedto form the therapeutic X-ray beam, and a pair of crossed lead bars 52and 54 which are mounted within ring 50. It will be noted that bars 52and 54 are substantially rectangular in cross section, their transversedimension being relatively small so as to define a relatively fine crosswhen viewed along the axis of ring while their depth parallel to axis 24is sufiiciently large to absorb incident X-rays striking the bars.

In operation the sight of Fig. 2 is mounted within either aperture 23 orone of the associated cones so that the juncture of bars 52 and 54 iscoincident with axis 24. Accordingly, when solenoid 40 is energized toproject low voltagesource 18 to its position coincident with axis 24, across will appear on fiuoroscope 44 owing to the fact that X-rays whichstrike bars 52 and 54 are absorbed, the juncture of the cross definingthe point at which axis 24 intercepts the fluoroscopic screen.

It will be recognized, of course, that numerous other forms of sightsmay be employed with the therapeutic X-ray apparatus of the invention.As shown in Fig. 3, for example, a ring sight comprising a lead ring 56mounted on a plastic base 58 may be employed in lieu of the sight shownin Fig. 2. As still another alternative fiuoroscope screen 44- may beintegrally connected mechanically to the therapeutic X-ray apparatushousing so that movement of the therapeutic X-ray source relative to thepatient will be accompanied by a corresponding movement in thefluoroscope screen. If this arrangement is employed the utilization of aseparate sight of the types shown in Figs. 2 and 3 may be avoided sincethe point at which axis 24 intersects the fiuoroscope screen is fixedand may be indicated by a simple marking on the screen.

In the foregoing description it has been assumed that fluoroscopictechniques were being employed during the initial positioning of thepatient. It is obvious, however, that an X-ray film cassette could alsobe employed in conjunction with the therapeutic X-ray source fordetermining the position of the region to be treated with respect to theaxis of the therapeutic X-ray source. It should also be clear from thedescription of the invention set forth hereinabove that its basicconcept resides in the utilization of a radioactive source of lowvoltage X-rays as a boresight for a therapeutic X-ray apparatus, and isnot to be restricted by the specific embodiment of the invention shownin Fig. 1.

With reference now toFig. 4, there is shown a modified form oftherapeutic X-ray apparatus, according to the invention, wherein lowvoltage source 18 is confined within its own apertured housing member 60which is hingedly mounted to main housing member 22, only a portion ofwhich is here shown. As indicated by the dotted line 61 in Fig. 4,housing member 60 has a normal or shielding position engaging a latch 62and is movable upon rotation of a keyed shaft 64 to an operatingposition in the mouth of the aperture in main housing member 22 wherebysource 18 is moved to a point intercepted by axis 24 of the therapeuticX-ray beam. It will be readily apparent to those skilled in the art thatshaft 64 may be rotated either manually or may be driven automaticallyby an air piston or similar fail safe mechanism. It should be noted toothat the apparatus may be made even further fail safe by designinghousing member 60 so that its center of gravity is always forward ofshaft 64.

The operation of the therapeutic apparatus shown in Fig. 4 issubstantially identical with the operation of the apparatus previouslydescribed with theexception that source 18 is moved into its operatingposition by a rotational rather than an axial movement. It is readilyapparent, of course, that sights of the general type shown in Figs. 2and 3 may also be employed in the apparatus of Fig, 4, in which instancethe sight may be permanently mounted within the beam forming aperture inhousing member 60.

In the two embodiments of the invention thus far disclosed it has beenassumed that the novel alignment device of the invention was beingemployed with a nucleonic or radioactive source of high voltagetherapeutic X-rays. It will be recalled, however, that the motivatingconcept of the invention is equally applicable to electronic therapeuticX-ray apparatus.

With reference now to Fig. 5, there is shown a sectional side elevationof a portion of an electronic therapeutic X-ray apparatus wherein thenovel alignment device of the invention is employed. As illustrated inFig. 5, the apparatus includes a conventional high voltage X-ray tube70, only a portion of which is shown, a beam forming member 72 whoseaxis 74 coincides with the axis of the therapeutic X-ray beam generatedat the target electrode of tube 70, a low energy radioactive source 76movable to a position coincident with axis 74, and an actuatormechanism, generally designated 78, for selectively moving source 76from a shielded position within the wall of member 72 to its positioncoincident with axis 74.

In the illustrative embodiment of the invention shown in Fig. 5 actuatormechanism 78 includes an arm 80 on one end of which radioactive source76 is mounted, the other end of arm 80 being aflixed to a shaft 82 whichis journaled in member 72 and which is rotatable through a gear train 84upon rotation of an input shaft 86. With reference now to Fig. 6, whichis a sectional View taken along section line 66 in Fig. 5, 'it will benoted that arm80 has a normal position within a cavity 88 in the wall ofmember 72, as indicated by the dotted line 90, and is movable in acounterclockwise direction until it engages a stop shoulder 92 in whichposition source 76 is coincident with the longitudinal axis of member72. It will again be readily apparent to those skilled in the art thatinput shaft 86 may be driven either manually or automatically, and thatthe actuator mechanism may include any of numerous mechanicalcontrivances to insure that the apparatus is completely fail safe.

It will of course be recognized that numerous other structuralembodiments of the basic concept of the invention will occur to thoseskilled in the art. In addition it is clear that the illustrativeembodiments shown and described may be modified in many particularswithout departing from the spirit of the invention. For example, thelow'energy source shown in Fig. 4, together with its encapsulatinghousing, could be employed readily with an electronic therapeuticapparatus rather than with a radioactive high energy source. Again, forcertain applications it would be permissible to permanently mount theboresight or low energy X-ray source in a position intercepted by theaxis of the therapeutic beam. Accordingly, it is to be expresslyunderstood that the invention is to be limited only by the spirit andscope of the appended claims.

What is claimed as new is:

1. In a therapeutic 'X-ray apparatus wherein a source of relatively highenergy X-rays is selectively operable to project a therapeutic X-raybeam along a predetermined axis, an alignment device forradiographically determining the position of the axis relative to anobject to be irradiated; said device comprising: a radioactive source oflow energy X-rays; means for normally shielding said radioactive source;selectively actuable means for moving said radioactive source from itsshielded position to a position coincident with the predetermined axis;and means for actuating said selectively actuable means.

2. A therapeutic X-ray apparatus comprising a first X- ray source forgenerating therapeutic X-rays; beam forming means for channeling X-raysfrom said first source along a predetermined axis to form a therapeuticX-ray beam; a second low voltage X-ray source for generating relativelylow energy X-rays, said low voltage source being movable to an operatingposition coincident with said predetermined axis; means coupled to saidbeam forming means for normally shielding said low voltage X-ray source;and a selectively operable actuating mechanism coupled to said lowvoltage source, said actuating mechanism being responsive to an inputsignal for moving said low voltage source to said operating positionwhereby a low energy X-ray beam is projected along said predeterminedaxis.

3. The therapeutic X-ray apparatus defined in claim 2 wherein said lowvoltage X-ray source is a specimen of thulium 170.

4. The therapeutic X-ray apparatus defined in claim 2 which furtherincludes a sight removably mounted in said beam forming means, saidsight including at least one element of relatively dense materialsubstantially intercepted by said axis, said sight being positionedbetween the object to be irradiated and said low voltage X-ray sourcewhen said low voltage source is in its operating position whereby theposition of said axis relative to the object may be determinedradiographically.

5. The therapeutic X-ray apparatus defined in claim 2 wherein said lowvoltage X-ray source consists essentially of a radioactive isotope andwherein said low voltage source is mounted within a housing member whichin turn is hingedly mounted at one end of said beam forming means, saidhousing member being apertured in one side to provide a beam formingchannel for said low voltage source and being rotatable into said beamforming means in response to operation of said actuating mechanism toproject a low voltage X-ray beam along said predetermined axis.

6. The therapeutic X-ray apparatus defined in claim 2 wherein said firstX-ray source consists essentially of a radioactive isotope.

7. The therapeutic X-ray apparatus defined in claim 2 wherein said firstX-ray source comprises an electronic X-ray machine including an X-raytube.

8. A therapeutic X-ray apparatus for treating a predetermined areawithin an object with high voltage therapeutic X-rays, said apparatuscomprising: a first radioactive source of relatively high energy X-rays;a shielding member surrounding said first source, said shielding memberhaving a substantially conically shaped bore in one side thereofcommunicating between said first source and the exterior of said member,said bore being operable as a beam forming channel for channeling highvoltage X-rays in a beam whose axis is coincident with the axis of saidbore; shutter means normally positioned within said bore for blockingirradiation therethrough; means coupled to said shutter means andresponsive to an input signal for withdrawing said shutter means fromsaid bore; a second radioactive source of relatively low energy X-rays,said second source being movable from a normal position to an operatingposition intercepted by the axis of said bore; shielding means forshielding said second source in its normal position; and means operableto move said second source to its operating position whereby said secondsource projects a low energy X-ray beam in line with the axis of saidbore to enable the radiographic determination of the position of theaxis relative to an object to be treated.

9. The therapeutic X-ray apparatus defined in claim 8 wherein saidshielding means for shielding said second source is connected to saidshielding member which surrounds said first source.

10. The therapeutic X-ray apparatus defined in claim 8 wherein saidshielding means for shielding said second source comprises a cavityformed in the surface of said conically shaped bore in said shieldingmember, and wherein said means operable to move said second source toits operating position comprises an axially movable pushrod coupled tosaid second source.

11. The method of aligning the axis of a therapeutic X-ray beam with anobject to be irradiated, said method comprising the steps of irradiatingthe object with a low voltage X-ray beam whose axis coincides with thatof the therapeutic beam, radiographically observing the position of theobject relative to said axis, moving the object relative to the axisuntil the object is intercepted by the axis, and irradiating the objectwith the therapeutic X-ray beam.

12. The method of determining radiographically the internal position ofan object to be irradiated relative to the axis of a therapeutic X-raybeam, said method comprising the use of a low energy radioactive sourcefor first irradiating the object with a low energy X-ray beam whose axiscoincides with the axis of the therapeutic beam.

13. The method of aligning the beam axis of a therapeutic X-ray machinewith a particular area within a patient to be treated, said methodcomprising the steps of irradiating the patient including the particulararea with a low energy X-ray beam from a point on the beam axis of thetherapeutic machine, radiographically observing the positional errorbetween the particular area and the beam axis, and moving the patientrelative to the therapeutic Y-ray machine until the particular area isintercepted by the beam axis.

14. The method defined in claim 13 which includes the additional stepsof masking 01f the area adjacent the particular area within the patientto be treated, and irradiating the particular area with the therapeuticX-ray beam.

References Cited in the file of this patent UNITED STATES PATENTS1,976,179 Mannl Oct. 9, 1934 2,486,503 Stephens Nov. 1, 1949 2,614,224Wright Oct. 14, 1952 2,675,479 Stewart et al. Apr. 13, 1954 2,730,566Bartow et al Ian. 10, 1956

